The bumper is your own to mess with as you please, knock yourself out! Go as simple or as elaborate as you want by adding quad patches and using subdivide with propagate box ticked.

Here's my rough one, I'm sure you can see where to detach the whole bumper if you want to swap for more detailed ones later, you could have a garage full of different bumpers for you moods!! For now mine is the aggressive \"road eater\" ;-)

You should have spotted 2 things, the running board under the door, it is a seperate patch stretched out and shaped, the windscreen has been detached, the hardtop roof is just temporary.

Go to the top view, detach the windscreen,move it over to the right then subdivide (with propagate ticked) the edge that was joining onto windscreen from the bonnet, you are trying to make a small enough distance between vertex points so you can pull out the piece that usually holds a windscreen on a car.